As is known, is frequently needed to measure magnetic fields accurately. For this purpose, various solutions have been proposed. In particular, there has already been proposed use of Hall sensors that exploit the well-known Hall effect, whereby, if a current flows through a conductor immersed in a magnetic field, the latter exerts a force transverse on the charge carriers that flow in the conductor and said force tends to “push” said charge carriers onto one side of the conductor. This effect is particularly evident in a thin flat conductor. The accumulation of the charges on the sides of the conductor determines a measurable voltage between the sides of the conductor itself and thus represents a measurement of the magnetic field.
A Hall sensor may be represented schematically as a resistive Wheatstone bridge, as illustrated in FIG. 1A, and is fabricated by forming resistive wells, for example implanted in a semiconductor or insulating substrate, accessible from outside by conductive pads P1-P4, as illustrated schematically, in top plan view, in FIG. 1B. The die of FIG. 1B provides a diffused resistive matrix, in which the resistive wells associated to two inputs I1 and I2 are electrically coupled to the resistive wells associated to two outputs O1 and O2, for example according to the connection scheme of FIG. 1A. Between the inputs I1 and I2 there flows, in use, a biasing, or control, current iBIAS. In the presence of a magnetic field B in which the resistive bridge of FIGS. 1A, 1B is immersed, the output voltage VHALL, measured as electrical potential difference that is set up across the outputs O1 and O2, assumes a value different from (greater in modulus than) the value that may be measured in resting conditions, i.e., in the absence of magnetic field B. Said variation is a function of the value of the magnetic field B in which the Hall sensor is immersed (the voltage VHALL is proportional to the magnetic field B).
Reading of the voltage VHALL enables acquisition of information on the magnetic field B (field intensity and direction). However, there may exist different elements that tend to limit the frequency response of the Hall sensor. For instance, the parasitic capacitances associated to the output nodes O1 and O2, which vary as a function of the dimensions of the Hall sensor, may limit the operating bandwidth to a few tens of kilohertz, which is insufficient for some types of applications (for example, the driver circuits for control of electric motors).
There is accordingly a need to provide a magnetic field sensor exploiting the Hall effect that is such as to overcome the drawbacks of the known art.